Prolonged constant load cycling exercise is associated with reduced gross efficiency and increased muscle oxygen uptake

Hopker, James G.; O’Grady, Ciaran; Pageaux, Benjamin

doi:10.1111/sms.12673

Cited by 37 publications

(31 citation statements)

References 41 publications

(66 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is supported by the findings of earlier studies where prolonged low-intensity exercise (2-3 h) increases VO2 in untrained to highly trained subjects. 5,6,29 Together with this gradually declining GE, we found an increased VE and RPE during exercise in both conditions, whereas no changes in RER, as an indicator of substrate oxidation, occurred. There are likely multiple explanatory factors for our findings; Increased VE has earlier been calculated to account for a small fraction (12-18%) of the variance in GE 30 and does not fully explain the change in GE found here.…”

Section: Discussionsupporting

confidence: 50%

“…The underlying mechanisms for the observed changes in GE during prolonged exercise, and the possible effects of intensity on this change, are not fully elucidated. 6 Changes in recruitment pattern of motor-units measured by integrated electromyography (iEMG) and median frequency have earlier been reported during high-intensity efforts and prolonged low-intensity cycling, partly explaining the drift in VO2. 7,11,12 Moreover, changes in pedaling technique might also play a role, since a positive correlation between earlier peak torque during the pedal stroke and improved 40min TT have been reported.…”

Section: Introductionmentioning

confidence: 92%

“…reduced GE) in well-trained cyclists. 5,6 This increase in VO2 seems to be intensity-dependent, where higher intensities lead to a greater drift in VO2 than lower intensity work. [7][8][9][10] It could, therefore, be hypothesized that inclusion of short high-intensity efforts performed during prolonged exercise would reduce GE further.…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

The Effect of 30-Second Sprints During Prolonged Exercise on Gross Efficiency, Electromyography, and Pedaling Technique in Elite Cyclists

Almquist¹,

Ettema²,

Hopker³

et al. 2020

International Journal of Sports Physiology and Performance

View full text Add to dashboard Cite

Background: Cycling competitions are often of long duration and include repeated high-intensity efforts. Purpose: To investigate the effect of repeated maximal sprints during 4 hours of low-intensity cycling on gross efficiency (GE), electromyography patterns, and pedaling technique compared with work-matched low-intensity cycling in elite cyclists. Methods: Twelve elite, male cyclists performed 4 hours of cycling at 50% of maximal oxygen uptake either with 3 sets of 3 × 30-second maximal sprints (E&S) during the first 3 hours or a work-matched cycling without sprints (E) in a randomized order. Oxygen uptake, electromyography, and pedaling technique were recorded throughout the exercises. Results: GE was reduced from start to the end of exercise in both conditions (E&S: 19.0 [0.2] vs 18.1 [0.2], E: 19.1% [0.2%] vs 18.1% [0.2%], both P = .001), with no difference in change between conditions (condition × time interaction, P = .8). Integrated electromyography increased from start to end of exercise in m. vastus lateralis and m. vastus medialis (m. vastus medialis: 9.9 [2.4], m. vastus lateralis: 8.5 [4.0] mV, main effect of time: P < .001 and P = .03, respectively) and E&S increased less than E in m. vastus medialis (mean difference −3.3 [1.5] mV, main effect of condition: P = .03, interaction, P = .06). The mechanical effectiveness only decreased in E&S (E&S: −2.2 [0.7], effect size = 0.24 vs E: −1.3 [0.8] percentage points: P = .04 and P = .8, respectively). The mean power output during each set of 3 × 30-second sprints in E&S did not differ (P = .6). Conclusions: GE decreases as a function of time during 4 hours of low-intensity cycling. However, the inclusion of maximal repeated sprinting does not affect the GE changes, and the ability to sprint is maintained throughout the entire session.

show abstract

Section: Discussionsupporting

confidence: 50%

Section: Introductionmentioning

confidence: 92%

See 1 more Smart Citation

The Effect of 30-Second Sprints During Prolonged Exercise on Gross Efficiency, Electromyography, and Pedaling Technique in Elite Cyclists

Almquist¹,

Ettema²,

Hopker³

et al. 2020

International Journal of Sports Physiology and Performance

View full text Add to dashboard Cite

show abstract

“…During prolonged, constant-work-rate exercise, an upward drift in pulmonary O 2 uptake (V O 2 ) is typically observed (9,25). The O 2 cost of such exercise may increase with time due to a shift in substrate utilization toward fat oxidation, a progressive recruitment of type II muscle fibers, or a decline in skeletal muscle mitochondrial and/or contractile efficiency (29).…”

Section: The Preexercise Elevation In Plasma [Nomentioning

confidence: 99%

Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O₂ uptake

Tan

Wylie

Thompson

et al. 2018

Journal of Applied Physiology

View full text Add to dashboard Cite

Nitrate-rich beetroot juice (BR) supplementation has been shown to increase biomarkers of nitric oxide availability with implications for the physiological responses to exercise. We hypothesized that BR supplementation before and during prolonged moderate-intensity exercise would maintain an elevated plasma nitrite concentration ([[Formula: see text]]), attenuate the expected progressive increase in V̇o over time, and improve performance in a subsequent time trial (TT). In a double-blind, randomized, crossover design, 12 men completed 2 h of moderate-intensity cycle exercise followed by a 100-kJ TT in three conditions: 1) BR before and 1 h into exercise (BR + BR); 2) BR before and placebo (PL) 1 h into exercise (BR + PL); and 3) PL before and 1 h into exercise (PL + PL). During the 2-h moderate-intensity exercise bout, plasma [[Formula: see text]] declined by ~17% in BR + PL but increased by ~8% in BR + BR such that, at 2 h, plasma [[Formula: see text]] was greater in BR + BR than both BR + PL and PL + PL ( P < 0.05). V̇o was not different among conditions over the first 90 min of exercise but was lower at 120 min in BR + BR (1.73 ± 0.24 l/min) compared with BR + PL (1.80 ± 0.21 l/min; P = 0.08) and PL + PL (1.83 ± 0.27 l/min; P < 0.01). The decline in muscle glycogen concentration over the 2-h exercise bout was attenuated in BR + BR (~28% decline) compared with BR + PL (~44% decline) and PL + PL (~44% decline; n = 9, P < 0.05). TT performance was not different among conditions ( P > 0.05). BR supplementation before and during prolonged moderate-intensity exercise attenuated the progressive rise in V̇o over time and appeared to reduce muscle glycogen depletion but did not enhance subsequent TT performance. NEW & NOTEWORTHY We show for the first time that ingestion of nitrate during exercise preserves elevated plasma [nitrite] and negates the progressive rise in O uptake during prolonged moderate-intensity exercise.

show abstract

“…During the initial seconds and minutes of steady state, submaximal endurance exercise (i.e., running and cycling), a sharp increase in HHb concentration arises (i.e., lower oxygen availability). The target muscle stays in a steady hypoxic state during the exercise once it reaches the voluntary rate of exertion ( Ufland, 2012 ; Hopker et al, 2016 ). It is not until near fatigue that the HHb concentrations start to rise sharply ( Hopker et al, 2016 ).…”

Section: Discussionmentioning

confidence: 99%

Effects of Resting, Consecutive, Long-Duration Water Immersions on Neuromuscular Endurance in Well-Trained Males

et al. 2018

View full text Add to dashboard Cite

Purpose: This study examined the effects of repeated long-duration water immersions (WI)s at 1.35 atmospheres absolute (ATA) on neuromuscular endurance performance. We hypothesized that, following 5 days of consecutive, resting, long-duration WIs, neuromuscular endurance performance would decrease.Methods: Fifteen well-trained, male subjects completed five consecutive 6-h resting WIs with 18-h surface intervals during the dive week while breathing compressed air at 1.35 ATA. Skeletal muscle endurance performance was assessed before and after each WI, and 24 and 72 h after the final WI. Muscular endurance assessments included 40% maximum handgrip endurance (MHE) and 50-repetition maximal isokinetic knee extensions. Near infrared spectroscopy was used to measure muscle oxidative capacity of the vastus lateralis and localized muscle tissue oxygenation of the vastus lateralis and flexor carpi radialis. Simultaneously, brachioradialis neuromuscular activation was measured by surface electromyography.Results: A 24.9% increase (p = 0.04) in the muscle oxidative capacity rate constant (k) occurred on WI 4 compared to baseline. No changes occurred in 40% MHE time to exhaustion or rate of fatigue or total work performed for the 50-repetition maximal isokinetic knee extension. The first quartile of deoxygenated hemoglobin concentration showed a 6 and 35% increase on WIs 3 and 5 (p = 0.026) with second quartile increases of 9 and 32% on WIs 3 and 5 (p = 0.049) during the 40% MHE testing when compared to WI 1.Conclusion: Our specific WI protocol resulted in no change to muscular endurance and oxygen kinetics in load bearing and non-load bearing muscles.

show abstract

Prolonged constant load cycling exercise is associated with reduced gross efficiency and increased muscle oxygen uptake

Cited by 37 publications

References 41 publications

The Effect of 30-Second Sprints During Prolonged Exercise on Gross Efficiency, Electromyography, and Pedaling Technique in Elite Cyclists

The Effect of 30-Second Sprints During Prolonged Exercise on Gross Efficiency, Electromyography, and Pedaling Technique in Elite Cyclists

Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O₂ uptake

Effects of Resting, Consecutive, Long-Duration Water Immersions on Neuromuscular Endurance in Well-Trained Males

Contact Info

Product

Resources

About

Prolonged constant load cycling exercise is associated with reduced gross efficiency and increased muscle oxygen uptake

Cited by 37 publications

References 41 publications

The Effect of 30-Second Sprints During Prolonged Exercise on Gross Efficiency, Electromyography, and Pedaling Technique in Elite Cyclists

The Effect of 30-Second Sprints During Prolonged Exercise on Gross Efficiency, Electromyography, and Pedaling Technique in Elite Cyclists

Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O2 uptake

Effects of Resting, Consecutive, Long-Duration Water Immersions on Neuromuscular Endurance in Well-Trained Males

Contact Info

Product

Resources

About

Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O₂ uptake